Heretofore, an acceleration sensor has been known, which includes: a rectangular weight portion that has a moving electrode; beams which support the weight portion freely swingably; and first and second fixed electrodes arranged so as to be opposed to the weight portion (for example, refer to Patent Literature 1). In the acceleration sensor as described above, a recessed portion is formed on the weight portion so that a rotation moment, in which a straight line (beam axis) that connects a pair of the beams to each other is used as a rotation axis, can be generated when acceleration is applied to the acceleration sensor. In such a way, one side and the other side in the weight portion, which are defined by the beam axis taken as a boundary line, are differentiated from each other in terms of weight.